“嗨,阿米戈!”
“您好,松鼠船长,先生!”
“现在我们要学习如何编写大项目。相应地,我们引入了一种新的任务类型:«大任务»。这是一个大任务,分解成许多小任务。在解决每个 «小任务时» 您将在现有代码中添加新代码,而不是从头开始编写代码。联邦的未来掌握在您的手中。”
“是的先生!”
“前五个 «大任务» 的目标是学习如何编写大型复杂项目。最初, «小任务» 的描述相当详细,有时甚至过于详细。后来,描述将变得更加笼统, “任务会变得越来越大。起初,任务只是“你的”代码的一小段。然后它们会变得更大。最终它们将成为整个框架(库)。”
“我准备好了,长官!”
“我试图让任务描述尽可能明确。但如果有什么不对:”
a) 考虑其他解释条件的方法。也许它并不像我希望的那样明确。
b) 尝试用几种不同的方法来解决它。
c) 寻求帮助或写信给我们;这些是新任务,我们很乐意在需要的地方“完善”它们。
“这是你的第一个任务:”
“今天我们将编写一个名为 «Hippodrome» 的小游戏。
“当我说我们时,我指的是你。我将成为你的导师。”
“条件呢?”
“什么条件,二等兵?你还在基础训练中吗?这是一个秘密的军事项目。启动IntelliJ IDEA。你会在那里找到这个任务的第一部分。后续的每个任务只有在你成功完成后才能使用上一个。滚出去!”
“是,长官!搬出去!”
“请记住,如果你的解决方案变得无可救药地混淆,你可以重置大任务并重新开始。右键单击任务列表插件中的大任务,你会看到一个包含各种选项的上下文菜单。”
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 1)
Today we'll write a small game called 'Hippodrome'.
And when I say we, I mean you. I will be your mentor.
To start, we'll need Hippodrome and Horse classes.
Create the Hippodrome and Horse classes.
And don't forget that every program starts with a main method.
Add one to the Hippodrome class.
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 2)
Hey, we've got a hippodrome, and it should have some horses.
So our hippodrome should store a list of its horses.
Add a List horses field to the Hippodrome class.
And to ensure that the horses won't be stolen, make this field private.
Add a getter for this field.
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 3)
Even though we've declared the horses variable, we haven't yet created the list itself (unless of course you've managed to get ahead of us).
Create a Hippodrome class constructor with one List parameter.
Save the passed list in the horses field (initialize the horses field).
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 4)
Now back to the horses. Every horse in a horse race must have a name and speed.
Our horses will simply run a certain amount of time (100 seconds or "steps").
The horse that runs the farthest is the winner.
Accordingly, we'll also need to store the distance the horse has already run.
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 5)
Finish writing the Horse class.
Add a constructor with name, speed, and distance parameters.
Add getters and setters for all the fields in the Horse class.
Make all of the methods public unless indicated otherwise.
12
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 6)
Now let's move on to the Hippodrome class and the main method.
We need to create a Hippodrome object and add some horses to it.
To start, in the Hippodrome class:
Create a static Hippodrome game field.
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 7)
But that's not all. We need to make the horses run.
Add run, move, and print methods to the Hippodrome class. Without parameters.
The move method will control the movement of all horses.
The print method will draw them on the screen.
And the run method manages it all.
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 8)
Make a loop from 1 to 100 in the run method. This will be our race.
In the body of the loop, we'll call move first, then print.
To prevent the whole loop from finishing in a split second, add Thread.sleep(200); as well.
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 9)
Now let's return to the move and print methods. Let's start with move.
In the Hippodrome class's move method, we call the move method on each horse in the loop.
Yes, you're right: the Horse class doesn't have it yet.
This means you need to add your own move method to the Horse class. :)
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 10)
We still need to write the Hippodrome class's print method.
Everything is simple here, too: In a loop, we call the print method on each horse.
Oh, and display 10 empty lines after the loop (using System.out.println()) to make it more beautiful.
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 11)
We're almost done with the Hippodrome class.
Add a call to run() at the end of the main method.
Hint:
The run() method is not static, so you can only call it on an object.
But where do you get the object?
Hint 2:
game.run();
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 12)
There's just a little left to do: finish writing the Horse class.
The move method is called each time a horse takes a step.
When the move method is called on a horse, the horse must run a certain distance.
The distance depends on the horse's speed.
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 13)
Now we'll return to the Horse class's print method.
Because we're working with the console, then all the racing horses will look something like this:
........Slevin
....Lucky
..........Homer
In other words, the print method should display a string consisting of dots and the horse's name.
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 14)
Time to enjoy our creation.
A new snapshot of the racetrack is displayed every half second.
Use the mouse to decrease the size of the console so that only one "snapshot" is visible at a time and remains in the same place.
Then you can watch the race live and even commentate.
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 15)
Add code to announce the winner.
We'll make two methods in the Hippodrome class:
public Horse getWinner() and public void printWinner()
The getWinner method must return the horse that has run the farthest.
The printWinner method displays the winner's name as follows:
The winner is <name>!
6
任务
Java Multithreading, 第 1 级, 课程 16
Hippodrome (part 16)
Now we're done for sure.
Add a call to the printWinner method to the end of the main method.
Launch and enjoy your first computer game. :)